Authentication mechanisms use one or more authentication factors to control access to secured services or devices. An authentication mechanism may require a knowledge factor (e.g., a username and a password), an ownership factor (e.g., a hardware security token), an inherence factor (e.g., a biometric identifier such as a fingerprint), or combinations thereof. The first of these is commonly referred to as proof of knowledge.
Authentication based on proof of knowledge includes a provisioning phase (e.g., enrollment) to define user knowledge, and a use phase to authenticate a user that proves that knowledge. Authentication based on conventional identity management techniques provides access control to secured services by validating a username and password to demonstrate proof of knowledge. Improved identity management techniques to authenticate a user employ picture passwords (rather than conventional textual passwords) that prove that the user has knowledge of a combination of input actions together with a known image such as a still picture, a motion picture with or without sound, a photograph, or the like.
Determining if a user should be authenticated using a picture password may be difficult in some situations or may be computationally intensive. As such, improved authentication methods are needed.